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Common questions about melatonin - Brand names: Circadin, Adaflex, Ceyesto, Slenyto, Syncrodin

How does melatonin work?

Melatonin is a natural hormone that is produced by the pineal gland in your brain. It helps control your sleep cycle.

The body produces melatonin just after it gets dark, peaking in the early hours of the morning and reducing during daylight hours. Melatonin acts on receptors in your body to encourage sleep.

Taking melatonin tablets adds to your body's natural supply of the hormone. This can help you get to sleep and improve the quality of your sleep.

How long does it take to work?

Melatonin takes around 1 to 2 hours to work.

How long will I take melatonin to treat insomnia?

For short-term insomnia you'll usually be prescribed melatonin for 1 to 4 weeks.

In some cases it can be prescribed for up to 13 weeks.

If you still have sleeping problems after finishing your course of melatonin, try making lifestyle changes that can help with insomnia.

See a doctor again if lifestyle changes do not help.

For some types of insomnia specialists may prescribe melatonin as a long-term treatment.

How does melatonin work for jet lag?

Melatonin can be taken as a short-term treatment for jet lag in adults.

There is some evidence that melatonin makes your symptoms less severe. It can also help reduce recovery time after a long flight by a day to a day and a half.

Jet lag can be common after travelling across several time zones in an easterly direction. It disturbs your sleep, your thinking and your digestion, and can make you feel irritable and tired during the daytime.

The usual dose is one 3mg tablet of melatonin but your doctor may recommend 2 tablets (6mg) if needed.

When you arrive at your destination, take melatonin at your normal bedtime (but not earlier than 8pm and not later than 4am).

You can use melatonin for up to 5 nights in a row.

Melatonin for jet lag may not be available for you on NHS prescription.

Will I sleepwalk with melatonin?

Taking melatonin has not been linked to sleepwalking.

If this happens to you, go back to a doctor for advice.

Can I get addicted to melatonin?

Melatonin is usually only recommended for short-term sleep problems. If you take it as prescribed, you're unlikely to become addicted to it.

However, ask a doctor or pharmacist for advice about stopping melatonin if you've been taking it for a long time or if you're worried about becoming dependent on it.

They can help you come off your medicine gradually.

Can I buy melatonin supplements at a health food shop?

In some countries, melatonin is available to buy in health food shops or online. It's sold as a complementary medicine and comes as standard capsules, tablets or a liquid that you drink.

However, these supplements are not authorised for sale in the UK and it's a prescription-only medicine.

Ordering melatonin online is not recommended. Find out more about the dangers of buying medicines online.

Will it affect my contraception or HRT?

Melatonin does not affect how contraception works, including the combined pill, progestogen-only pill or emergency contraception.

However, your levels of melatonin can increase when taking the combined pill or hormone replacement therapy (HRT).

Can I drive or ride a bike?

Do not drive a car, ride a bike or operate machinery if melatonin makes you sleepy, gives you blurred vision, or makes you feel dizzy, clumsy or unable to concentrate or make decisions.

This may be more likely when you first start taking melatonin, but could happen at any time, for example, when starting another medicine.

It's an offence to drive a car if your ability to drive safely is affected. It's your responsibility to decide if it's safe to drive. If you're in any doubt, do not drive.

Talk to a doctor or pharmacist if you're unsure whether it's safe for you to drive while taking melatonin.

GOV.UK has more information on the law on drugs and driving.

Can I drink alcohol while taking melatonin?

No. Try not to drink any alcohol while you're taking melatonin.

Alcohol and melatonin together can make you sleep very deeply, so you do not breathe properly and can have difficulty waking up.

Is there any food or drink I need to avoid?

Do not have drinks that contain caffeine (including tea, coffee, cola or energy drinks) while you're taking melatonin. Caffeine has the opposite effect of melatonin and stops it working properly.

Also try to avoid alcohol, as it can affect the way melatonin works.

Will recreational drugs affect it?

Using cannabis, heroin or methadone with melatonin will increase the medicine's sleep-inducing effects. You could go into a very deep sleep and have difficulty waking up.

Stimulant drugs such as cocaine and amphetamines have the opposite effect to melatonin and will stop it working to help you sleep.

Talk to a doctor if you think you might use recreational drugs while you're taking melatonin.

You can find out more about the side effects of recreational drugs on the Frank website.

Can lifestyle changes help with insomnia?

There are a number of things you can do to help your insomnia:

  • set regular times for going to bed and waking up
  • relax before bedtime – try taking a warm bath or listening to calming music
  • use thick curtains or blinds, an eye mask and earplugs to stop you being woken up by light and noise
  • avoid caffeine, cigarettes (including e-cigarettes), alcohol, heavy meals and exercise for a few hours before going to bed
  • do not watch TV or use phones, tablets or computers just before going to bed
  • do not nap during the day
  • write a list of your worries, and any ideas about how to solve them, before you go to bed to help you forget about them until the morning

Some people find sleeping tablets you can buy in a pharmacy helpful. But these do not cure insomnia and can have unwanted side effects.


Do not take any medicines or herbal remedies that make you feel sleepy while taking melatonin.

They can increase the drowsy-making (sedating) effects of your medicine.

Page last reviewed: 13 February 2023
Next review due: 13 February 2026